Purpose
In acute ischemic stroke with unknown time of onset, magnetic resonance (MR)‐based diffusion‐weighted imaging (DWI) and fluid‐attenuated inversion recovery (FLAIR) estimates lesion age to guide intravenous thrombolysis. Computed tomography (CT)‐based quantitative net water uptake (NWU) may be a potential alternative. The purpose of this study was to directly compare CT‐based NWU to magnetic resonance imaging (MRI) at identifying patients with lesion age < 4.5 hours from symptom onset.
Methods
Fifty patients with acute anterior circulation stroke were analyzed with both imaging modalities at admission between 0.5 and 8.0 hours after known symptom onset. DWI‐FLAIR lesion mismatch was rated and NWU was measured in admission CT. An established NWU threshold (11.5%) was used to classify patients within and beyond 4.5 hours. Multiparametric MRI signal was compared with NWU using logistic regression analyses. The empirical distribution of NWU was analyzed in a consecutive cohort of patients with wake‐up stroke.
Results
The median time between CT and MRI was 35 minutes (interquartile range [IQR] = 24–50). The accuracy of DWI‐FLAIR mismatch was 68.8% (95% confidence interval [CI] = 53.7–81.3%) with a sensitivity of 58% and specificity of 82%. The accuracy of NWU threshold was 86.0% (95% CI = 73.3–94.2%) with a sensitivity of 91% and specificity of 78%. The area under the curve (AUC) of multiparametric MRI signal to classify lesion age <4.5 hours was 0.86 (95% CI = 0.64–0.97), and the AUC of quantitative NWU was 0.91 (95% CI = 0.78–0.98). Among 87 patients with wake‐up stroke, 46 patients (53%) showed low NWU (< 11.5%).
Conclusion
The predictive power of CT‐based lesion water imaging to identify patients within the time window of thrombolysis was comparable to multiparametric DWI‐FLAIR MRI. A significant proportion of patients with wake‐up stroke exhibit low NWU and may therefore be potentially suitable for thrombolysis. ANN NEUROL 2020;88:1144–1152